First, we propose to study the in vitro packaging of bacteriophage lambda DNA, with the intent of purifying the unfilled head precursor and the maturable DNA. The goal is to define the interacting species and establish the requirements for efficient packaging. Secondly, the injection process will be investigated to learn how a phage particle functions in injection. We will investigate further the phage membrane receptor interaction, the triggering of DNA release and its entry into the cell.